BldCancerDoc

Male donors and female donors who have not had a child are preferred. There is higher risk of a post-transplant complication called graft-versus-host disease (GVHD) if the donor is a woman who has previously borne a child. This happens because mothers blood is sensitized against the baby's blood (when the child in in the womb) - so even though we have may have an immune matched donor, we are not completely able to account for this "immune sensitization" that happens during pregnancy. As a result there is a higher chance of the patient (recipient) getting GVHD, where the donor cells are "hyperactive" and mount an immune attack against the recipient's normal tissues. Hence, the preference for male donors or female donors who have not been previously pregnant. However, at the end of the day, there are several factors besides the sex of the donor that go into making decisions about the best donor for a given patient.

If you consider the diversity of the human genome, there are a very large number of permutations and combinations of which gene's we inherit. Hence, even though the registry has ~15 million donors registered, we still struggle with finding donors for some patients.

Here is a story I can share - many years ago, I had a young patient with bone marrow failure disease (bone marrow was empty - it was not making any blood cells - in medical terms, he had severe aplastic anemia). He was very sick, with many bad infections and other complications because of chemotherapy. He received a bone marrow transplant from his sibling donor - he is now 8 years out, really doing well, father of two beautiful daughters. Again, highlights the resilience, endurance and courage our patients have as they go through this process.

It is also a matter of representation within the registry - certain racial/ethnic groups are well represented in the registry (e.g., Whites of European descent). Hence, despite the genetic diversity, just with the fact that there are more donors available in this group, the probability/chances of finding a donor is greater. The chances of finding a good matched donor is lower among patients who are from a racial/ethnic minority group that is not well represented in the registry. We also face issues with finding good matched donors among patients with mixed race.

As you live longer and in remission (without the disease coming back), the lesser the likelihood of your disease coming back after transplant. Things start to look very encouraging at 1 to 2 years post-transplant. Once my patients are at 5 years, I start getting more comfortable with using the word "cure". However, there is a very very very small risk of the disease coming back in patients who are >5 years post-transplant - hence the importance of regularly following with your doctor.